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HC-SR04 Ultrasonic Module

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Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function.
The ranging accuracy can reach to 3mm.
The modules includes ultrasonic transmitters, receiver and control circuit.

Basic principle of work

  • Using IO trigger for at least 10us high level signal,
  • The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back.
  • IF the signal back, through high level , time of high output IO duration is the time from sending ultrasonic to returning.
  • Test distance = (high level time×velocity of sound (340M/S) / 2


  • Easy to assemble
  • Compatible with Raspberry Pi and Arduino and so on.


  • Working Voltage DC 5 V
  • Working Current 15mA
  • Working Frequency 40Hz
  • Max Range 4m
  • Min Range 2cm
  • MeasuringAngle 15 degree
  • Trigger Input Signal 10uS TTL pulse
  • Echo Output Signal Input TTL lever signal and the range in proportion
  • Dimension 45*20*15mm

Pin Definitions

  • 5V Supply
  • Trigger Pulse Input
  • Echo Pulse Output
  • 0V Ground


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Timing Diagram

The Timing diagram is shown below. You only need to supply a short 10uS pulse to the trigger input to start the ranging, and then the module will send out an 8 cycle burst of ultrasound at 40 kHz and raise its echo.
The Echo is a distance object that is pulse width and the range in proportion .
You can calculate the range through the time interval between sending trigger signal and receiving echo signal.

Formula: uS / 58 = centimeters or uS / 148 =inch; 
or: the range = high level time * velocity (340M/S) / 2

we suggest to use over 60ms measurement cycle, in order to prevent trigger signal to the echo signal.



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Package Includes

  • 5 x Ultrasonic sensor

How to use


  • Ultrasonic sensor, distance sensor, Raspberry Pi 4B, arduino